cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-10 of 11 results. Next

A037308 Numbers whose base-2 and base-10 expansions have the same digit sum.

Original entry on oeis.org

0, 1, 20, 21, 122, 123, 202, 203, 222, 223, 230, 231, 302, 303, 410, 411, 502, 503, 1130, 1131, 1150, 1151, 1202, 1203, 1212, 1213, 1230, 1231, 1300, 1301, 1402, 1403, 1502, 1503, 1510, 1511, 2006, 2007, 2032, 2033, 2102, 2103, 2200, 2201, 3006, 3007, 3012
Offset: 1

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Author

Keywords

Comments

n is in the sequence iff n+(-1)^n is in the sequence. [Robert Israel, Mar 25 2013]

Examples

			122 is a member, since digital-sum_2(122) = 5 = digital-sum_10(122).
		

Crossrefs

Programs

  • Maple
    N:= 10000; # to get all elements up to N
    select(x -> (convert(convert(x,base,10),`+`)-convert(convert(x,base,2),`+`)=0), [$0..N]); # Robert Israel, Mar 25 2013
  • Mathematica
    Select[Range[0, 5000], Total[IntegerDigits[#, 2]] == Total[IntegerDigits[#, 10]] &] (* Jean-François Alcover, Mar 07 2016 *)
  • PARI
    is(n)=hammingweight(n)==sumdigits(n); \\ Charles R Greathouse IV, Sep 25 2012
    
  • Python
    def ok(n): return sum(map(int, str(n))) == sum(map(int, bin(n)[2:]))
    print(list(filter(ok, range(3013)))) # Michael S. Branicky, Jun 20 2021
  • Sage
    [n for n in (0..10000) if sum(n.digits(base=2)) == sum(n.digits(base=10))] # Freddy Barrera, Oct 12 2018
    

Formula

From Reinhard Zumkeller, Aug 06 2010: (Start)
A007953(a(n)) = A000120(a(n));
A180018(a(n)) = 0. (End)

Extensions

Edited by N. J. A. Sloane Nov 29 2008 at the suggestion of Zak Seidov

A135120 Numbers such that the digital sum base 2 and the digital sum base 3 and the digital sum base 10 all are equal.

Original entry on oeis.org

1, 21, 222, 223, 1230, 1231, 1502, 2200, 2201, 3012, 3013, 10431, 12214, 12215, 12250, 12251, 14102, 15003, 15021, 16011, 20040, 20041, 22130, 23211, 23230, 23231, 24003, 30070, 30071, 30105, 30231, 30321, 31005, 31150, 31151, 31420
Offset: 1

Views

Author

Hieronymus Fischer, Dec 24 2007

Keywords

Examples

			a(2)=21, since ds_2(21)=ds_3(21)=ds_10(21)=3.
		

Crossrefs

Programs

  • Mathematica
    Select[Range[5000], Total[IntegerDigits[#, 2]] == Total[IntegerDigits[#, 3]] ==  Total[IntegerDigits[#, 10]] &] (* G. C. Greubel, Sep 26 2016 *)
  • PARI
    is(n)=my(t=sumdigits(n)); t==hammingweight(n) && t==sumdigits(n,3) \\ Charles R Greathouse IV, Sep 26 2016

A135121 Numbers such that the digital sum base 2 and the digital sum base 3 and the digital sum base 5 all are equal.

Original entry on oeis.org

0, 1, 6, 7, 10, 11, 60, 61, 180, 181, 285, 300, 301, 575, 687, 754, 826, 827, 882, 883, 900, 901, 910, 911, 1254, 1305, 1311, 1326, 1327, 1335, 1377, 1383, 1386, 1387, 1395, 1431, 1506, 1507, 1532, 1626, 1627, 1650, 1651, 1890, 1891, 1955, 2013, 2036, 2040
Offset: 1

Views

Author

Hieronymus Fischer, Dec 31 2007

Keywords

Examples

			a(2)=6, since ds_2(6)=ds_3(6)=ds_5(6), where ds_x=digital sum base x.
		

Crossrefs

Programs

  • Mathematica
    Select[Range[0,3000],Length[Union[Total/@IntegerDigits[#,{2,3,5}]]]==1&] (* Harvey P. Dale, Sep 04 2014 *)

Extensions

Added 0, Stanislav Sykora, May 06 2012

A135127 Numbers such that the digital sums in bases 2, 3, 5 and 7 all are equal.

Original entry on oeis.org

0, 1, 882, 883, 1386, 1387, 2502, 2503, 3453, 7555, 7652, 7665, 7931, 9751, 10101, 12250, 12251, 16893, 17010, 17011, 17515, 17550, 17551, 18285, 20301, 22050, 22051, 24406, 24407, 25053, 27503, 31654, 40930, 40931, 41951, 50878, 50879
Offset: 1

Views

Author

Hieronymus Fischer, Dec 31 2007

Keywords

Examples

			a(2)=882, since ds_2(882 )=ds_3(882 )=ds_5(882 )=ds_7(882 )=6, where ds_x=digital sum base x.
		

Crossrefs

Programs

  • Mathematica
    Select[Range[0, 32000], Total[IntegerDigits[#, 2]] == Total[IntegerDigits[#, 3]] == Total[IntegerDigits[#, 5]] == Total[IntegerDigits[#, 7]] &] (* G. C. Greubel, Sep 27 2016 *)
    Select[Range[0,51000],Length[Union[Total/@IntegerDigits[#,{2,3,5,7}]]] == 1&] (* Harvey P. Dale, Sep 18 2019 *)

Extensions

Added 0, Stanislav Sykora, May 06 2012

A135122 Numbers such that the digital sum base 2 and the digital sum base 3 and the digital sum base 4 all are equal.

Original entry on oeis.org

1, 21, 261, 273, 17748, 17749, 20820, 20821, 65620, 65621, 70740, 70741, 83268, 83269, 86292, 86293, 1066068, 1066069, 1070420, 1135701, 1135893, 1135953, 5326161, 5330001, 5330241, 5330260, 5330261, 5506389, 5525829, 5526801, 5571909, 5574933, 5592321
Offset: 1

Views

Author

Hieronymus Fischer, Dec 31 2007

Keywords

Examples

			a(2)=21, since ds_2(21)=ds_3(21)=ds_10(21)=3, where ds_x=digital sum base x.
		

Crossrefs

Programs

  • Mathematica
    Select[Range[5600000],Length[Union[Table[Total[IntegerDigits[#,n]],{n,2,4}]]]==1&] (* Harvey P. Dale, Aug 14 2013 *)
  • PARI
    isok(n) = my(sd2=sumdigits(n, 2)); (sd2==sumdigits(n, 3)) && (sd2==sumdigits(n, 4)); \\ Michel Marcus, Aug 08 2018

Extensions

a(31)-a(33) from Giovanni Resta, Aug 06 2018

A135123 Numbers such that the digital sum base 2 and the digital sum base 3 and the digital sum base 6 all are equal.

Original entry on oeis.org

1, 12, 13, 114, 115, 366, 367, 477, 687, 864, 865, 876, 877, 1086, 1087, 1305, 1326, 1327, 1386, 1387, 1596, 1597, 1626, 1627, 1656, 1657, 1746, 1747, 1836, 1837, 1956, 1957, 2595, 2607, 2646, 2647, 3276, 3277, 3906, 3907, 3948, 3949, 4068, 4069, 5438
Offset: 1

Views

Author

Hieronymus Fischer, Dec 31 2007

Keywords

Examples

			a(2)=12, since ds_2(12)=ds_3(12)=ds_6(12), where ds_x=digital sum base x.
		

Crossrefs

Programs

  • Mathematica
    Select[Range[5000], Total[IntegerDigits[#, 2]] == Total[IntegerDigits[#, 3]] == Total[IntegerDigits[#, 6]] &] (* G. C. Greubel, Sep 26 2016 *)

A135124 Numbers such that the digital sums in base 2, base 4 and base 8 are all equal.

Original entry on oeis.org

1, 64, 65, 4096, 4097, 4160, 4161, 262144, 262145, 262208, 262209, 266240, 266241, 266304, 266305, 16777216, 16777217, 16777280, 16777281, 16781312, 16781313, 16781376, 16781377, 17039360, 17039361, 17039424, 17039425, 17043456
Offset: 1

Views

Author

Hieronymus Fischer, Dec 31 2007, Dec 31 2008

Keywords

Comments

Written as base 64 numbers the sequence is 1,10,11,100,101,110,111,1000,1001, ... (cf. A007088)

Examples

			a(7)=4161, since ds_2(4161 )=ds_4(4161 )=ds_8(4161 ), where ds_x=digital sum base x.
		

Crossrefs

Programs

  • Mathematica
    Select[Range[500000], Total[IntegerDigits[#, 2]] == Total[IntegerDigits[#, 4]] == Total[IntegerDigits[#, 8]] &] (* G. C. Greubel, Sep 26 2016 *)
    With[{k = 64}, Rest@ Map[FromDigits[#, k] &, Tuples[{0, 1}, 5]]] (* Michael De Vlieger, Oct 28 2022 *)
    Select[Range[171*10^5],Length[Union[Total/@IntegerDigits[#,{2,4,8}]]]==1&] (* Harvey P. Dale, May 14 2025 *)
  • PARI
    a(n) = fromdigits(binary(n),64); \\ Kevin Ryde, Apr 02 2025

Formula

a(n) = (1/2)*Sum_{k=0..floor(log_2(n))} (1-(-1)^floor(n/2^k))*64^k.
G.f.: (1/(1-x))*Sum_{k>=0} 64^k*x^(2^k)/(1+x^(2^k)).

Extensions

Edited by N. J. A. Sloane, Jan 17 2009

A135125 Numbers such that the digital sum base 2 and the digital sum base 5 and the digital sum base 10 all are equal.

Original entry on oeis.org

1, 1300, 1301, 5010, 5011, 7102, 7103, 10050, 10051, 10235, 11135, 12250, 12251, 14015, 16102, 16103, 20060, 20061, 20206, 20207, 23230, 23231, 32012, 32013, 32302, 32303, 32410, 32411, 44000, 44001, 45010, 45011, 50012, 50013, 50300
Offset: 1

Views

Author

Hieronymus Fischer, Dec 31 2007

Keywords

Examples

			a(2)=1300, since ds_2(1300)=ds_5(1300)=ds_10(1300), where ds_x=digital sum base x.
		

Crossrefs

Programs

  • Mathematica
    Select[Range[10000], Total[IntegerDigits[#, 2]] == Total[IntegerDigits[#, 5]] == Total[IntegerDigits[#, 10]] &] (* G. C. Greubel, Sep 27 2016 *)

A135126 Numbers such that the digital sums in bases 3, 4, 5 and 6 all are equal.

Original entry on oeis.org

1, 2, 188, 668, 908, 1388, 1628, 2170, 2171, 2830, 2831, 3908, 4330, 4331, 6490, 6491, 8650, 8651, 10390, 10391, 10629, 12792, 12793, 12794, 17110, 17111, 17290, 17291, 25930, 25931, 36312, 36313, 36314, 37812, 37813, 37814, 41532, 41533, 41534
Offset: 1

Views

Author

Hieronymus Fischer, Dec 31 2007

Keywords

Examples

			a(3)=188, since ds_3(188)=ds_4(188)=ds_5(188)=ds_6(188)=8, where ds_x=digital sum base x.
		

Crossrefs

Programs

  • Mathematica
    Select[Range[3000], Total[IntegerDigits[#, 3]] == Total[IntegerDigits[#, 4]] ==  Total[IntegerDigits[#, 5]] == Total[IntegerDigits[#, 6]] &] (* G. C. Greubel, Sep 27 2016 *)

A135128 Numbers such that the digital sums in bases 2, 3, 5 and 10 all are equal.

Original entry on oeis.org

1, 12250, 12251, 23230, 23231, 32410, 32411, 45010, 45011, 51130, 51131, 52030, 52031, 54010, 54011, 100053, 100090, 100091, 100305, 102250, 102251, 107002, 107003, 110134, 110170, 110171, 110350, 110351, 110460, 110461, 113050, 113051
Offset: 1

Views

Author

Hieronymus Fischer, Dec 31 2007

Keywords

Examples

			a(2)=12250 since ds_2(12250 )=ds_3(12250 )=ds_5(12250 )=ds_10(12250 )=10, where ds_x=digital sum base x.
		

Crossrefs

Programs

  • Mathematica
    Select[Range[32000], Total[IntegerDigits[#, 2]] == Total[IntegerDigits[#, 3]] == Total[IntegerDigits[#, 5]] == Total[IntegerDigits[#, 10]] &] (* G. C. Greubel, Sep 28 2016 *)
    Select[Range[120000],Length[Union[Total/@IntegerDigits[#,{2,3,5,10}]]]==1&] (* Harvey P. Dale, Mar 30 2024 *)
Showing 1-10 of 11 results. Next